---
title: "Configure the Advanced IO Function"
url: https://docs.catalyst.zoho.com/en/tutorials/third-party-auth/nodejs/config-advancedio/
description: "Integrate Auth0 SPA authentication service with basic web applications hosted on Catalyst using OpenID Connect and 0Auth2.0 authentication protocols."
last_updated: 2026-08-17T12:16:04Z
service: All Services
type: tutorial
related_links:
  - name: "Third-party Authentication type"
    url: /en/cli/v1/initialize-resources/introduction
  - name: "Advanced IO Function"
    url: /en/serverless/help/functions/advanced-io/
  - name: "Third-party Authentication SDK"
    url: /en/sdk/nodejs/v2/cloud-scale/authentication/third-party-server-token/
  - name: "Auth0 Help Documentation"
    url: https://auth0.com/docs
---

# Configure the Advanced IO Function

Now, we will begin coding the authorization portal application by configuring the function component.

The [function’s directory](https://docs.catalyst.zoho.com/en/cli/v1/project-directory-structure/functions-directory), (`functions/custom_token_generation`), contains:
* The `ndex.js` main function file
* The `catalyst-config.json` configuration file
* Node modules
* [`package.json`](https://docs.npmjs.com/files/package.json) and [`package-lock.json`](https://docs.npmjs.com/configuring-npm/package-lock-json.html) dependency files

Before you start adding code, you need to install the following packages to ensure all required dependencies are satisfied.
* **Express**: The [`express`](https://www.npmjs.com/package/express) package is required to handle HTTP routes
* **Axios**: The [`axios`](https://www.npmjs.com/package/axios) package is required to handle outgoing HTTP requests

Navigate to the function folder present in the `functions/custom_token_generation` directory and install the following packages using the command shown below:

```sh
npm install express axios --save
```

![catalyst_tutorials_third_party_package_install](https://catalyst-docs-development.zohostratus.in/images/tutorials/third-party-auth/catalyst_tutorials_third_party_package_install.webp)

You will be adding code in the `index.js` file.

The Advanced IO function contains the following functionalities:

<table border="1" cellpadding="8" cellspacing="0">
  <thead>
    <tr>
      <th>Endpoint</th>
      <th>Request Method</th>
      <th>Purpose</th>
      <th>Possible Expected Responses</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>`/getauth`</td>
      <td>`GET`</td>
      <td>
        <ul>
            <li>Will read the Auth0 access token from the `zc-customauth` header.</li>
            <li>Will call the Auth0 `/userinfo` and will generate a custom web token using the returned user details.</li>
        </ul>
      </td>
      <td>Returns the required **Catalyst Custom Token** (JSON) or a **401** if no token is obtained.</td>
    </tr>
    <tr>
        <td>`/catalystUser`</td>
        <td>`GET`</td>
        <td>Initializes Catalyst using request context and retrieves the details of the authenticated user.</td>
        <td>Returns a JSON containing the end-user details.</td>
    </tr>
  </tbody>
</table>

Copy the code below and paste it into the `index.js` files of your project using an IDE and save the files.

> **Note:** Go through the code in this section to make sure you fully understand it.

**index.js**

```javascript
'use strict'
// Import Catalyst Node SDK
const catalyst = require('zcatalyst-sdk-node')
// Import Express framework
const express = require('express')
const app = express()
// Initialize express middleware
app.use(express())
// Import axios to make HTTP requests to Auth0
const axios = require('axios')
// Header name where Auth0 access token is expected
const auth0TokenHeader = 'zc-customauth'
// Replace with your Auth0 domain (example: https://your-domain.auth0.com)
const auth0Domain = '{replace your Auth0 domain}'
// Endpoint to validate Auth0 token and generate Catalyst custom token
app.get('/getauth', async (req, res) => {
  try {
    // Read Auth0 access token from request header
    const auth0AccessToken = req.headers[auth0TokenHeader]
    // Auth0 user info endpoint
    const auth0Url = auth0Domain + '/userinfo'
    // Proceed only if token is provided
    if (auth0AccessToken !== undefined) {
      const url = auth0Url
      // Attach Authorization header with Bearer token
      const config = {
        headers: {
          Authorization: 'Bearer ' + auth0AccessToken
        }
      }
      // Call Auth0 to fetch user details
      const auth0response = await axios.get(url, config)
      // Initialize Catalyst app using request context
      const catalystApp = catalyst.initialize(req)
      // Generate Catalyst custom web token using Auth0 user details
      const tokenObj = await catalystApp.userManagement().generateCustomToken({
        type: 'web',
        user_details: {
          email_id: auth0response.data.email,
          first_name: auth0response.data.given_name,
          last_name: auth0response.data.family_name
        }
      })
      // Send generated Catalyst token back to client
      res.status(200).send(JSON.stringify(tokenObj))
    } else {
      // If Auth0 token is missing in header
      res.status(401).send({ status: 'failure', message: 'Token not provided in the header' })
    }
  } catch (error) {
    // Log error and return failure response
    console.log(error)
    res.status(error.response.status).send({ status: 'failure', message: 'An unexpected error has occured. Please try again after sometime.' })
  }
})
// Endpoint to fetch the currently authenticated Catalyst user
app.get('/catalystUser', async (req, res) => {
  try {
    // Initialize Catalyst using request context
    const catalystApp = catalyst.initialize(req)
    // Retrieve current logged-in Catalyst user
    const currentUser = await catalystApp.userManagement().getCurrentUser()
    // Send user details as response
    res.status(200).send(JSON.stringify(currentUser))
  } catch (error) {
    // Handle and log any unexpected errors
    console.log(error)
    res.status(500).send({ status: 'failure', message: error })
  }
})
// Export the Express app
module.exports = app
```

> **Note:** Ensure you provide domain generated by Auth0 in line **14**.